A fluorinated compound is useful as a surface treating agent since it has high lubricity, water/oil repellency, etc. By imparting water/oil repellency to a substrate surface by such a surface treating agent, stains on the substrate surface will easily be wiped off, and stain removability will be improved. Among such fluorinated compounds, a fluorinated ether compound having a poly(oxyperfluoroalkylene) chain in which an ether bond (—O—) is present in the middle of a perfluoroalkyl chain is particularly excellent in the fat and oil stain removability.
A surface treating agent containing such a fluorinated ether compound is useful in applications wherein it is desired to maintain a performance (abrasion resistance) whereby the water/oil repellency is less likely to be reduced even if repeatedly rubbed by fingers, and a performance (fingerprint stain removability) whereby fingerprints deposited on a surface can easily be removed by wiping, for a long period of time, e.g. as a surface treating agent for a member constituting a surface to be touched by a finger, of a touch panel.
As such fluorinated ether compounds, specifically, fluorinated ether compounds of the following (1) to (4) are known.
(1) A fluorinated ether compound having a structure wherein (CF2O) units and (CF2CF2O) units are randomly linked, and having a hydrolysable silyl group at a terminal (Patent Document 1)
(2) A fluorinated ether compound having a structure wherein at least two types of units selected from the group consisting of (CF2O) units, (CF2CF2O) units, (CF2CF2CF2O) units and (CF(CF3)CF2O) units are randomly linked, and having a hydrolysable silyl group at a terminal (Patent Documents 2 to 5)
(3) A fluorinated ether compound having a structure wherein only (CF2CF2CF2O) units or (CF(CF3)CF2O) units are linked, and having a hydrolysable silyl group at a terminal (Patent Documents 6 and 7)
(4) A fluorinated ether compound having a structure wherein only (CF2CF2CF2CF2O) units are linked, and having a hydrolysable silyl group at a terminal (Patent Document 8)